title: Urinary type IV collagen as a predictor for the incidence of microalbuminuria in young patients with Type 1 diabetes.
abstract: OBJECTIVE
  To clarify whether urinary type IV collagen-to-creatinine ratio is a predictor for the incidence of microalbuminuria in patients with Type 1 diabetes.
  
  
  METHODS
  A longitudinal observational cohort study was conducted; the subjects included normoalbuminuric patients diagnosed with Type 1 diabetes before the age of 30 years and who were less than 40 years old at the start of the observation. In total, 225 patients were enrolled (age, mean ± SD: 25 ± 5 years; male: 32.9%). The endpoint was the incidence of microalbuminuria, defined as 30 mg/g Cr ≤ urinary albumin-to-creatinine ratio < 300 mg/g Cr. Patients were divided into two groups based on the median of urinary type IV collagen-to-creatinine ratio levels.
  
  
  RESULTS
  During the median follow-up period of 8.8 years (range 1.0-12.8 years), 13 patients with high urinary type IV collagen-to-creatinine ratio progressed to microalbuminuria. Meanwhile, only one patient with low urinary type IV collagen-to-creatinine ratio reached the endpoint. Kaplan-Meier estimates for the time to reach the endpoint were significantly faster for patients with a high ratio than for those with a low ratio (log-rank test, P < 0.001). In the multivariate Cox hazard analysis, the hazard ratio for patients with high vs. low urinary type IV collagen-to-creatinine ratio was 13.51 (95% CI 1.59-115.02, P = 0.017). When urinary type IV collagen-to-creatinine ratio was treated as a continuous variable, logarithmically transformed urinary type IV collagen-to-creatinine ratio, but not baseline albumin-to-creatinine ratio, was independently associated with reaching the endpoint (hazard ratio 19.23, 95% CI 1.53-242.30, P = 0.022).
  
  
  CONCLUSIONS
  Urinary type IV collagen may be an important predictor for the incidence of microalbuminuria in young patients with Type 1 diabetes.
authors.affiliation: Diabetes Center, Tokyo Women's Medical University School of Medicine, Tokyo; Department of Internal Medicine 1, Shimane University Faculty of Medicine, Shimane, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Morita
authors.forename: K
authors.initials: K
authors.lastname: Hanai
authors.forename: Y
authors.initials: Y
authors.lastname: Uchigata
mesh_terms: D000293:Adolescent; D000328:Adult; D000419:Albuminuria / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology*; D015415:Biomarkers / Q000652:urine*; D024141:Collagen Type IV / Q000652:urine*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000453:epidemiology* / Q000378:metabolism; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D011379:Prognosis; D055815:Young Adult
chemical_list: D015415:Biomarkers; D024141:Collagen Type IV; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human